The boiler firebox of a power-generating boiler facility extends upwards for many stories. When repairs are to be made, an elaborate procedure is currently required in order to access the superheater section of the boiler. This superheater section is located seven to ten stories above the floor of the firebox. It is accessed by a motorized climbing scaffold to ferry a crew to the superheater tubes, where scaffolding must be constructed.
Prior to using the motorized scaffolding, however, it is necessary to first construct a scaffolding onto the pendant section of the superheater. The tubes of the pendant and platen sections are then deslagged. The deslagging procedure is necessary, because the clinkers that have developed around the superheater tubes during the firing of the boiler can weigh as much as half a ton. Should these clinkers accidentally break off during the upward travel of the motorized scaffold, serious injury could occur to the scaffold workers. Therefore, it is imperative that these clinkers be initially removed, and then an ash hopper throat scaffold installed at the bottom of the firebox so as to support a motorized scaffolding. The cables for the motorized scaffolding are then lowered from the boiler roof and tied off at the proper length. The motorized scaffold is subsequently assembled at the floor of the firebox, and a crew thereafter raised to the platen elevation. Using the previously installed pendant scaffold and the motorized scaffold as base locations, another scaffolding is then erected to access the leak in the superheat tubes. Thereafter, the leak is repaired by removing the bad section of the tube and welding a new section in its place.
Once the repair has been accomplished, it then becomes necessary to retrace all of the aforementioned steps to disassemble the scaffold rigging. These steps include removing the pendant scaffold, lowering and disassembling the motorized scaffold, removing the motorized scaffold cables and removing the ash hopper throat scaffold.
As is evident, the above procedure is quite elaborate, time-consuming and expensive.
The present invention incorporates a new type of telescoping scaffolding that can access the superheater section from the seventh-story entrance hatch. As a result, most of the prior procedural steps can be eliminated. The telescoping scaffolding eliminates the need for deslagging, as the motorized scaffolding is no longer required. Installing the ash hopper throat scaffold, as well as the cabling for the motorized scaffolding, is, likewise, no longer necessary.
In a test run with a Babcock and Wilcox RB608 boiler, the invention has saved over $150,000 in the repair of the superheater. These savings will be realized for every subsequent repair.
While it is useful to deslag the superheater tubes periodically, this procedure can be done while the tube repair is in progress. Thus, the clean-up procedure can be more efficiently scheduled during the repair sequence.